In recent years, a variety of chemiluminescence methods (CL method) have been developed, which include, for instance, an enzyme immunoassay (EIA) that utilizes an antigen-antibody reaction, a chemiluminesence immunoassay (CLIA) in a narrow sense in which a chemical illuminescent compound is used for labeling as a tracer for immunoassay, and a chemilluminescent enzyme immunoassay (CLEIA) which detects enzyme activity with high sensitivity by using a chemical luminescent compound in a detection system.
As an inspection method using any of the techniques as described above, there have been known the magnetic particle method using magnetic particles each having a surface coated with an antigen or an antibody, the latex method using latex having a surface coated with an antigen or an antibody, the beads method using spheric beads each having a surface coated with an antigen or an antibody, or the so-called tube coating method using cells each having an inner wall coated with an antigen or an antibody. When taking into account efficiency of capturing an antigen or an antibody as well as production cost and running cost, However, methods using magnetic bodies such as magnetic particles or beads are far more advantageous.
In the conventional type of inspection methods using a magnetic material as described above, however, it is required to clean the magnetic material or have the magnetic material reacted to a reagent by gathering the magnetic material floating or depositing in a reactor, such as a specimen reaction container, or generating a floating state thereof several times in the reactor, however, it is extremely difficult to maintain high precision of gathering or agitating the magnetic material in the process, and this is one of the reasons why the inspection method making use of magnetic material has not been automatized for various applications.
Description is made of a flow in an immuno chemical process making use of a magnetic material as described above with reference to FIG. 9. In this flow, at first when a required quantity of specimen is sampled in a container 1 with a first pipette device P.sub.1 in step (a), a reaction insoluble magnetic liquid 3 is poured into the container 1 by a second pipette device P.sub.2 in step (b). Agitation by a vibrating agitator is executed in step (c), incubation (under a constant temperature) is executed in step (d), and attraction of magnetic material by a magnet M and discharge of the liquid are executed in step (e). A cleaning liquid is then poured by a third pipette device P.sub.3 into the container in step (f).
Then in step (g), agitation is carried out by an shaking agitator, in step (h), the magnetic material 2 is attracted by the magnet M with the cleaning liquid discharged, in step labeling liquid 6 is poured in through a fourth pipette device P.sub.4, in step (j) agitation is carried out by a shaking agitator, in step (k) incubation (reason under a constant reaction) is carried out, then in step (l) the magnetic material is attracted by the magnet M with the reaction liquid discharged, in step (m) the cleaning liquid is poured in through a fifth pipette device P.sub.5. Then, in step (n), agitation is carried out by the shaking agitator.
Then, for instance, in CLEIA method, in step (o) the magnetic material 2 is attracted by the magnet M with the cleaning liquid discharged, in step (p) the carried liquid is poured in, in step (q) agitation is carried out by a shaking agitator, and then in step (r) the sample is left for a certain period of time, and in step (s) the quantity of light emitted from the reaction system is measured with an optical measuring instrument such as PMT.
On the other hand, in case of CLIEA method, after step (n) described above, in step (t) a cleaning liquid containing the magnetic material 2 in the vessel 1 is sucked out with the cleaning liquid poured into a measuring cell with a filter provided thereon, and the magnetic material 2 contained in the cleaning liquid is collected by the filter. Then, in step (u), hydrogen peroxide liquid (H.sub.2 O.sub.2) is poured into the magnetic material 2 collected by said filter to have liquid emitted transitionally, and a quantity of emitted light is measured by PMT tightly protected against light coming from outside.
On the other hand, in a checking method, like the CLEIA method or EIA method, in which light emission is continued for a certain period of time after a substrate liquid is poured in step (s), in step (t) a quantity of light generated in the reaction is measured with an optical measurement instrument such as a PMT.
The above description relates to the conventional type of inspection method using a magnetic material, but as clearly understood from the foregoing, in the conventional inspection method making use of the type of magnetic material as described above, it is required to attract the magnetic material onto the internal wall of a container and then homogeneously diffuse the attracted magnetic material into a liquid several times. It is extremely difficult to execute separation of the magnetic material from a liquid, agitation, and cleaning the container at high precision, a problem to be solved.
Namely, when separating the magnetic material from a liquid, in the conventional type of inspection method, generally magnetic attraction is produced on a side wall of a large container, requiring a long time to attract any magnetic material diffused in a liquid onto the internal wall of the container. Efficiency in gathering the magnetic material thus is disadvantageously very low.
Also, when gathering magnetic material on the internal surface of a container and inserting a pipette into a liquid to absorb the liquid, the magnetic material may be absorbed together with the liquid, and it is extremely difficult to completely capture the magnetic material.
Furthermore, when agitating the liquid with magnetic material diffused therein, generally to eliminate magnetism in a magnet and mix and diffuse the magnetic material once absorbed in liquid in the container, vibration is usually employed. However, it is difficult to diffuse the magnetic material in the liquid homogeneously, and the liquid containing the magnetic material mixed therein sometimes splashes out onto an upper surface of the container, another problem to be solved. As a result, with vibration as employed agitation in the conventional technology, a washing off the liquid containing magnetic material splashed out onto the upper surface of the container is required. Hence, processing becomes more complicated, and if this operation for washing off the liquid is carried out incompletely, the subsequent steps in the process are seriously affected.
Furthermore, when cleaning the liquid and magnetic material in the container as described above, materials other than those deposited on the surface of the magnetic material are removed by carring out processes for separating as well as agitating as described above, but the same problems as those that arise in separating and agitating may occur.
Also, in the inspection method making use of the conventional type of magnetic material, if a reaction process or a treatment process is a very specific one, it is required to build mechanisms for separation, agitation, and cleaning as well as a control system suited to the specific process. Hence, the mechanisms or the control system become very complicated, and it is practically impossible to carry out an inspection making use of a magnetic material based on a very specific reaction or treatment process. As a result, the facility or the operating cost becomes very high.
In addition, in the method of gathering magnetic material based on the aforementioned conventional technology, it is difficult to position the magnet as described above in such a container as, for instance, a microplate, and even if possible, it is difficult to position a magnet on a side face of the container. It is also difficult to carry out separation by attracting the magnetic material from a liquid, agitation and cleaning, and as a result it is extremely difficult to downsize the container by using a microplate, a fatal disadvantage.